Bristlecone/Foxtail Site #1: Cirque Peak

I have some odds and ends in inventory about bristlecone and foxtail sites, which I’m going to post up, mostly because I find the information rather interesting. Most dendrochronologists assume that the bristlecone/foxtail sites are far too remote to have experienced direct human effects. As far as I’m concerned, this is an assumption that needs to be proven. There was widespread mining activity in the American Southwest in the 19th century, evidenced now by ghost towns. The mines were nearly all underground mines, all of which use timber for roof support. This happens to be something that I know about. I’ll show examples in a couple of Colorado locations. My hunch is that many of the roads used by Graybill to reach the bristlecone sites were originally developed to access small 19th century mines. I’ll show some examples of this – there are some striking examples. There’s no special reason for starting with Cirque Peak. I’m not making big claims about this material, other than I find it interesting.

CIRQUE PEAK

Cirque Peak (ca530) is a Graybill site foxtail pine site, which is a very strong contributor to the MBH98 PC1. The WDCP archive shows a sample location reported at 3627N, 11813W and 3505m (11,500 ft). Foxtails are inter-related with bristlecones – they are located in the Sierra Nevadas, while the bristlecones are in the White Mountains on the other side of I-395 on this map. A zoom-out showing the location of this detail is at sherpaguides.com here as Area 46 on the zoom-out map. A very detailed gazetteer of California locations is here. A map of California counties is here.

Cirque Peak is in Inyo County. The summit of Cirque Peak is at 362837N, 1181410W 3900 m (12900 ft), which is to the N and W of the sample location and which is presumably very close to Cirque Lake located at 362835N, 1181306W. The town of Lone Pine, indicated to be to the north of the map area, is at 363622N, 1180343W and is between (latitude) Cirque Peak and the next closest foxtail sites at Timber Gap (3627N) and (Flower Lake 3646N.) The South Fork of the Cottonwood Creek goes from near the location of the foxtails down to the Owens Valley.

Compared to other parts Sierra Nevada, the foxtail pine’s distribution is relatively unaffected by human activity. Over 75% of its distribution is within Sequoia and Kings Canyon National Parks, and a good deal outside of that is found in National Forest Wilderness Areas (SNEP Science Team, 1996). Given the difficulty in access to foxtails, they have for the most part fallen outside the range of human impact.

One major exception to this was a period of logging in the East Sierras during the 1870’s. The Cerro Gordo mine, across Owens Valley from the Sierran foxtails near Cottonwood Creek, had completely exhausted the timber supply of the Inyo/Coso Range and thus set its eyes on the Sierras. In 1873 a sawmill was built in Cottonwood Canyon, [363753N 1171740W] and logging of lodgepole and foxtail pines began. Logs were sent down nearly 6000ft to the Owens Valley floor, burned in charcoal kilns, brought by boat across Owens Lake, and then brought up 4000ft to the Cerro Gordo smelters [363222N 1174727W] high in the Inyo Mountains. By 1893, however, the mill was defunct following a bust at the mine (Clark and Clark, 1987). Though the mining lasted a short period, its effects are readily seen today in stumps and downed logs near Cottonwood Creek. Foxtail pines forests do not regenerate quickly and thus are very vulnerable to disturbance.

The southern part of the Sierran foxtail’s distribution was also heavily grazed in the late 1800’s and early 1900’s causing permanent meadow damage, though possible effects of this period on foxtails have not been studied (Storey and Usinger, 1963). Much reduced intensity grazing continues today, but given the small number of cattle and their preference for meadows, foxtails are most likely not impacted. I have found no evidence of cattle presence in any foxtail pine forests as of yet, but they are present in meadows just below the foxtail forests near Cottonwood Creek (Bogan, personal observation). Reference: Storey, T.I. and Usinger, R.L. 1963. Sierra Nevada Natural History. Berkeley: UC Press. 374p.

We mentioned some references to high sheep grazing in the 19th century in our E&E article, which is a pretty interesting topic as far as I’m concerned, since 19th century sheep grazing is associated with a growth pulse for other trees (due to removal of grass competition). I’m not saying that this is proven for bristlecones, only that the effect has to be eliminated.

CERRO GORDO
Cerro Gordo is located at 363222N 1174727W just to the east of I395. On the above map, the town of Bartlett on I-395 is at 362836N 1180148W.

Sometimes a serendipitous relationship exits between a ghost town and a modern city. Such is the case with Cerro Gordo, the "Fat Hill" silver mining city high in the Inyo Mountains of Owens Valley. "Cerro Gordo stands undisputedly as the Inyo County camp of greatest production," wrote historian W. A. Chalfant in The Story of Inyo. Credit for the silver discovery in 1865 is usually given to Pablo Flores and two other Mexicans. Some stories suggest mining activities long before Flores set foot on the mountain.

In any case, Cerro Gordo’s major development took place in the early 1870s ramrodded by Mortimer Belshaw and Victor Beaudry. By 1872, the camp was producing 100 to 150 83-pound bars of silver- lead each day. These bars, called "loaves" because of their resemblance to loaves of bread, were shipped in huge wagons to the nearest ocean port city, which happened to be Los Angeles. At the port, the silver was loaded onto ships that carried it to San Francisco and other destinations for final refining.

The wagons did not return empty to Cerro Gordo. They carried all manners of necessities, from building materials to liquor and food to the camp of several thousand inhabitants. The commerce caused the little town of Los Angeles to grow. With growth came a thirst that could only be quenched by a steady supply of water.

L. A.’s thirst was temporarily quenched in 1913 when William Mulholland completed an aqueduct bringing Owens Valley water into Los Angeles. The project, all 233 miles of it, was built between 1908 and 1913. It is still considered a marvel of 20- century engineering….
The famous "Yellow Grade" climbs over 5500 feet in 7.5 miles from Owens Valley to the townsite of Cerro Gordo.

UPDATE: Mar 30., 2005. Here is a diagram of the Cirque Peak ring width growth and site chronology. You’ll notice the different look of the "grass" diagram than for Polar Urals or Tornetrask because of the longer-lived trees. The red portion is the post-1980 results.

50 Comments

My topo map has the Cottonwood Mill at 362751N and 1180840W (NAD27) at about 9300 ft. The foxtail site is about 5 miles to the west with an elevation change of about 2000 ft. The foxtail site is located near Chicken Spring Lake and Cottonwood pass. The site is at timberline and is rocky with quite sparse vegetation. Protect you food from the bears if you are backpacking. I have been the area a number of times in the last few years and have noticed some large older foxtail pines in the Horseshoe Meadow trailhead and campground which is only several miles from the mill location. My guess is that the loggers cut trees in the Cottonwood creek drainage and didn’t get to Chicken Spring Lake area. Livestock would have stay in the Horseshoe and Big Whitney meadow area or been driven south to Mulkey meadows.

Phil, thanks for this comment. One of the benefits of throwing thoughts on the Internet about particularized sites is that you stand a chance of running into someone with specialized knowledge of them. I’ll post up some info on Timber Gap in a day or two which may interest you. Steve

I don’t know if you are aware that USGS has a database of mines and other activities such as quarries called Mindat. That data has been converted to a form which can be overlayed on commercial mapping software, in particualar the DeLorme consumer mapping software.

Steve,
My second try at a reply- first disappeared when I tried to send it.

I originally developed a Cirque Peak chronology as part of my dissertation back in the late-70’s and early 80’s (long before and independent of the Graybill work). Five points that will help understand the area. 1) Treeline along the southwest slopes of Cirque Peak is fairly distant from any roadhead and shows no sign of disturbance (one of the reasons why I picked this site to work on). Many of the old time Lone Pine cowboys that I met while doing my work suggested that they never went up that way because it was too rocky, 2) the area where I worked was just above Chickenspring Lake and along the crest to the northwest for about a kilometer, 3) Graybill’s site is at the far northwestern edge of my study area at approximately the same elevation- there is also no evidence of disturbance at this site. It is closer to and almost directly to the south of the Cirque Peak name on the map you posted, 4) I know of no evidence of mining in either area, and probably most important- 5) I chose to avoid sampling strip bark trees. My chronology is virtually identical to Graybill’s Cirque Peak chronology until approximately 1850AD when the Graybill chronology begins to diverge. The non-strip bark trees that I sampled do not show the big increase in growth recorded by Graybill.

Other possibly notable things about the area in question include the nature of the drainage. Most drainages along the Eastern side of the Southern Sierra are shorter and steeper. This area has well developed drainage and disection compared with areas a bit to the north. This is also where the amount of snow begins to trail off due to the influence of the Pacific High. The Oct – May storm track simply misses this part of the mountains more of the time versus say Mammoth. The crest here is starting to get lower – the peaks are below 13 and you start to see more trails and roads nearly reaching or through the passes. Whereas, a few miles to the north, a crossing may involve mountaineering, down at these latitudes is become more walkable / ridable ( and further down, of course, drivable). Who knows if any of these things matter vis a vis ring widths. The strip bark vs non strip bark seems to be of greater and greater interest.

No. I have not sampled strip bark trees since the first set of cores that I took in 1979 (which included some strip bark trees). The strip bark trees were so remarkably different from the normal trees that I chose to avoid them when I sampled in 1981 for the chronology I reported in my dissertation. I doubt that after 27 years I still even have these cores. I do remember having a very interesting conversation with Val LaMarche in 1983 about the large increase in growth they were about to report in their 1984 CO2 fertilization paper. I was having problems with the paper (I was given a copy by Val to informally review) since the chronology reported in that paper was only illustrated back to 1800 AD. Val knew of my work in the Sierra Nevada and we often talked about the differences between my site and those in the White Mountains. I asked how they explained the large increase in growth just prior to 1800 AD and also just prior to 1600 AD which I was recording in my Cirque Peak chronology as a sawtooth pattern- and which I knew was in their chronologies as well. I noted that in all likelihood the pre-1600 runup and pre-1800 runup could not be attributed to CO2 fertilization and that in fact they (and the runup that they were attributing to CO2 fertilization) appeared to be part of a periodic ~200 year growth pattern. I never got a good answer from any of the authors about that one.

On another note with regard to separate thread on temperature sensitivity of these trees, I still believe that these trees are temperature limited. In the late 90’s and lasting for 4 years I had temperature sensors at treeline at Cirque Peak. There is a high correlation between temperatures recorded at this site and at surrounding temperature stations (data from CDEC stations at Tyndall Creek, Bighorn Plateau, Crabtree Meadows, Chagoopa Plateau, etc). Sensor temperatures also correlate highly with those at Giant Forest which I used in my temperature reconstructions. Tree growth does appear to be primarily limited by temperature. Snow depth/water availability at this site does not seem to be an issue. For most of my dissertation work I would monitor snow depth either by hiking in in winter/spring or by climbing peaks to the south and viewing the area with high powered binoculars. Almost always snow covered from the onset of the first snows until mid-to-late May. When I would hike in in early summer when the foxtails were beginning their seasonal growth I would dig soil pits in the root zone and evaluate soil moisture content. Could always find relatively moist soil in the root zone early in the season. Late summer it was almost always dry- but by that time ring growth had effectively ended for the year. Really do not think that these trees are moisture limited.

Thanks for the thoughtful reply, Louis. What do you make of the fact that Salzer & Kipfmueller (2005) (full citation and discussion found in the bcp various threads) used bcps to reconstruct BOTH temp and precip?

Have read the paper and compared with my 2000 year precipitation reconstruction for the four corners region based on precipitation sensitive trees only. Very good match with what I have. I am not certain about the temperature signal and have always had problems with the response surface approaches that claim to be able to extract both temperature and precip from the same record.

Not sure where you are going with this? Probably should have been clearer in my response #12. I don’t have a regional (SW) temperature record to compare directly with Salzer’s from the San Francisco Peaks. I do have a regional precipitation reconstruction that can be directly compared. The precip reconstruction of Salzer was taken from lower forest border sites only. Dendroclimatic theory would suggest that these sites are limited by moisture availability. Remember that a given species can have different responses at different elevational limits. The match to my unpublished data for southwest precipitation is actually quite excellent. Adjusted R2 is 0.738. Even higher when you only consider sites within 200km of the San Francisco Peaks. When you consider that I used 117 low elevation sites that exhibit very high correlations to the NOAA divisional precipitation data and a non-significant response to temperature, it suggests that at lower tree line BCP sites used by Salzer show a very strong and independently reproducable regional precip. signal (no BCP sites included in my reconstruction). The correlation between my 117 site precip. reconstruction and Salzer’s temperature reconstruction from high upper treelines sites in the San Francisco Peaks is a highly insignificant 0.028. This is as I would expect if he had extracted a distinct precip. signal from precipitation sensitive sites and an equally distinct temperature signal from an independent BCP record responding to temperature alone. Perhaps the problem here is that you are not allowing that trees at different elevations can have responses to different climatic variables? Even foxtail pine at their upper and lower limits in the Sierra Nevada and BCP in the White Mountains exhibit different responses at their upper and lower limits.

My comment on response surfaces probably confused things. Response surfaces are an approach that extracts both temperature and precipitation from the same record. See Graumlich 1991. I am not a believer in this approach. In the Salzer case they did not use response function analysis and the records that were used to extract temperature and precipitation were from independent BCP sites at the elevational limits (upper and lower) of growth.

Where I’m going with this is simple. As I’ve stated in several of the bcp posts, I’m trying to understand to what extent the anomalous uptick in 20th c. strip-bark bcp growth could be a result of positive synergy between multiple limiting factors, especially Temp, Precip, and CO2. And then whether a similar model might apply, only to a lesser degree, with the full-bark samples.

Given that there are no hard and fast empirical rules guiding the process of site & species selection to deliver proxies of known accuracy – only botanical intuition regarding limiting factors and experience in terms of observed growth responses – it seems to me this is a reasonable null hypothesis.

The reason for my questioning in detail & mentioning Salzer & Kipfmueller (2005) is because you say:

Tree growth does appear to be primarily limited by temperature. Snow depth/water availability at this site does not seem to be an issue.

I’m trying to understand the extent to which this statement might apply to sites other than the ones you studied. e.g. What range of site types, species, and growth forms. Again, the reason is simple: there is no proxy-building recipe book for site selection. But wouldn’t it be nice to have one? In that sense I’m not going anywhere with this. It’s an open-ended discussion that will go wherever you lead it.

The other question I’d like answered is to know what kind of process one must go through in order to get permission to sample these various bcp areas. I’ve never worked in the Southwest on high-elevation pines. So, naturally, I’m curious. As somebody who’s worked with bcps I’m curious to know what all you know. That’s all.

Happy to provide info. I consider strip bark growth to be an anomalous growth form not really amenable to standard dendroclimatic analysis because the mechanism relating this growth to climate is uncertain. I (and probably most others) am not really certain how strip bark growth relates to photosynthetic area, root area and other metrics that drive conifer growth. It is also quite possible that the strip bark growth mechanism has little to do with climate – in which case the models for strip bark growth and normal trees might be quite different. I am not aware of any studies that have looked at this- not really my area of expertise.

I wish there was a cookbook. Find this type of tree in this setting and you will get a clean temperature or precipitation signal. That would be great. What I have found over the years is that the signal that you get for a given species can be partially predicted by site- namely very high gives a primary temperature signal while very low gives a precipitation signal. But I have also been surprised at times by reconstructions that differ from this pattern. Usually can be resolved to some local factor such as wind patterns (rapidly ablate away snow cover at high elevations for instance and you can get a precip sensitive tree at an otherwise temperature sensitive site) or local drainage (trees in a water collecting hollow can have little to no precipitation signal even though their surrounding trees on stable surfaces show a strong precip. signal). I have a recent paper (McAuliffe et al., 2006 Global and Planetary Change 50:184-201) that illustrates this with pinyon pines that are on a slope that eroded rapidly in the early 1900’s. This erosion exposed most of the roots denying the trees access to moisture. Even though this was a very wet period in the southwest the trees on the eroded slopes show what I term “geomorphic drought” with reduced growth while those on stable surfaces show a large increase in growth between 1906 and 1930. The slope trees are completely out of sync with the regional climate signal while the stable surface trees a short distance away (100 to 500 meters away from the slope) correlate beautifully with the regional climate signal. The climate growth response gets back in sync again as soon as the trees are able to establish a new deeper root system and regain access to moisture.

As for getting a permit to sample BCP- I always contact the Forest Service or Park Service depending on the site. Usually have to supply a work plan and specify what you are collecting and for what purpose. Depending on the agency can take as little as a month or two to get the required permits, or in some sensitive areas can take over six months. In the White Mountains there might be some additional restrictions (not really certain) because of ongoing studies. I was just up there at Sheep Mountain in September downloading some temperature sensors that I have placed at upper treeline and it was clear that someone had sampled there recently (possibly both live trees and remnant samples).

Haven’t followed this discussion long enough to know what your background is. Glad to help you get up to speed on the BCP’s. Maybe we can meet some time at some high elevation BCP site in the western US.

Steve,
I traversed the local area of each of Lisa’s sites many times in the 70’s and 80’s before she did her work but have not been to the actual sites sampled in the late 80’s and 90’s. The trees in all of these areas do not look very different from what is found at Cirque Peak or what is found on the eastern side of the crest in Cottonwood Basin. Usually a mix of full bark and strip bark trees for the living trees and numerous standing snags above the living tree limit. Sorry I can’t help you more on this. Last time I went back in to this area in the late-90’s the local bears got my food bag forcing me into a long and hungry march out. Unfortunately never got to her sites.

Can you point me to the part of S&K where they use bcp for precipitation?

This is all I found, in section 2.2:

Three lower forest border tree-ring chronologies were used in the
precipitation reconstruction (Figure 2). Through the process of
crossdating, measured ring-widthseries of construction timbers from
archaeological sites are appended to the earlier portions of measured
series from living trees at the three sites to substantially lengthen the
records. The chronologies are derived from ponderosa pine (P. ponderosa),
pià’¹à ”non (P. edulis), and Douglas-fir (P. menziesii) from elevations of
approximately 1,890–2,290 m in northern Arizona (Flagstaff and Canyon de
Chelly) and southern Utah (Navajo Mountain)

Three lower forest border tree-ring chronologies were used in the
precipitation reconstruction (Figure 2). Through the process of
crossdating, measured ring-widthseries of construction timbers from
archaeological sites are appended to the earlier portions of measured
series from living trees at the three sites to substantially lengthen the
records. The chronologies are derived from ponderosa pine (P. ponderosa),
pià’¹à ”non (P. edulis), and Douglas-fir (P. menziesii) from elevations of
approximately 1,890–2,290 m in northern Arizona (Flagstaff and Canyon de
Chelly) and southern Utah (Navajo Mountain)

I don’t understand how they know the growth location or the trees that they have used for their reconstruction of the earlier sections of the records. While the location of the current trees are known, how does one determine if a tree grew at the “lower forest border” 500 years ago?

Can you point me to the part of S&K where they use bcp for precipitation?

Hmmm, no I can’t. Because on re-reading the article more carefully, you are correct: they used different species & sites for temp vs. precip reconstructions. This is my mistake. [What happened was I scanned the paper, saw the reference to “Colorado plateau”, trolled for feedback, didn’t get anything, set the paper aside, and proceeded to other matters while running with my mistaken impressions.] My apologies to the authors, Steve M, and readers of CA for mischaracterizing their methods.

RE: #10 – “Tree growth does appear to be primarily limited by temperature. Snow depth/water availability at this site does not seem to be an issue. For most of my dissertation work I would monitor snow depth either by hiking in in winter/spring or by climbing peaks to the south and viewing the area with high powered binoculars. Almost always snow covered from the onset of the first snows until mid-to-late May. When I would hike in in early summer when the foxtails were beginning their seasonal growth I would dig soil pits in the root zone and evaluate soil moisture content. Could always find relatively moist soil in the root zone early in the season. Late summer it was almost always dry- but by that time ring growth had effectively ended for the year. Really do not think that these trees are moisture limited.”

How certain are we that the point at which “ring growth had effectively ended for the year” was really known with great certainty? Probing further, is there any correlation between the actual point where growth started to slow for each given year with soil moisture? For example, during a year where soil moisture lasted longer due to summer convective events, might the growth limit due to incident solar energy and temperature, whereas, during a year where most moisture was from lingering snow pack moisture, might the growth trail off well prior to the lowering of sun angle and temperature? Have any truly difinitive studies of this been done?

Re #22
This creates a minor wrinkle in terms of how I phrase the question. Still, the underlying question itself is valid: to what extent is the 20th c. uptick in growth (P. longaeva and/or P. ponderosa/edulis) a product of positive synergy between T, P, and other factors, such as CO2? I understand the idea behind the S&K2005 Fig. 1 climate response gradient. This is their theoeretical justification for fitting two different models (G=P, G=T) to the two different series. What I would like to see is the same statistical model fit to both series: G=(T,P,C), including all 2-way interactions. Their Table II doesn’t do this.

Rather than dismiss the strip-bark samples, I would like to know whether it might be the strength of synergistic interactions within these samples that boosts the slope of the response.

It’s a simple question, really. I want to know why the strip-barks and full-barks diverge in the mid 1800s. Everyone says it’s a mystery. I don’t care for mystery stories. I want to see an analysis.

I have a question Louis might or might not be able to answer. Do they make any adjustment when it comes to strip-bark Bcps as to the growth curve? I’ve mentioned before that it would seem likely that the smaller amount of cambium would mean that the root system put out by that bark would be able to put out tendrils over a larger area since they wouldn’t have to compete with roots from an entire tree. The net result would be that the thickness of growth in a given year would be larger even if the total wood produced would be less. Therefore, since the adjustment of trees over time is because they gradually stop producing as much wood, might not strip bark versions act like much younger trees than the total age of the tree? It’d be nice if it were possible to gather cores from the dead wood of the stripbark trees which would allow you to see when the wood moved from complete bark to strip bark and whether or not later rings were thicker.

bender, Graumlich 1991 argued that the foxtail growth was synergistic between T and P, but with stronger partial correlation to P. Re Louis’ comment about soil moisture, I’ve seen similar comments by Fritts 1969 about bcps but in the context that growth stopped when soil moisture fell below a certain level. As I recall, summer precipitation tended not to make much difference to bcps as it presumably ran off rather quickly on the slopes.

One could certainly picture a synergistic situation in which the trees grew until they ran out of winter precipitation in the soil; with a nonlinear response to temperature.

Another point that I recall seeing in a Fritts article – and maybe Louis can comment – was that inversions were common in valleys and that cold inversions had a role in limiting growth as well. (I’ll have to double check this remark some time)

I can’t locate the link, but there is a paper out there (by a Forest Service guy, I think) that suggests growth rates at these sites is controlled by the amount of snowpack. I tend to agree with Graumlich and Fritts. If you have Growth = aT + bP + cTP +e, couldn’t you easily have decent correlations with both variables? In fact, T and P are so inter-related at sites like this that the correlation between the interaction term is probably the best. Has anyone looked at it this way? Evapotranspiration?

RE: #26 – the typical winter inversion layer will reside anywhere between just above local ground level and about 7 thou. Places typically affected would be Reno, Bishop, Truckee, etc. Once you get into the Alpine Zone, inversions are of little direct consequence, other than the occasional odd cirumstance where it is 20 deg F with ice fog in Reno (~ 4K feet elevation) meanwhile it’s 40 with sun at High Camp at Squaw Valley USA (~8200 feet).

“The foxtail pine response surface analyses presented in this study suggest a third type of temperature-precipitation interaction in which drought stress limits growth in years of low winter precipitation and cool temperatures limit growth in years of high winter precipitation. While the contribution of precipitation in governing growth of subalpine trees in the southern Sierra Nevada and the nearby White Mountains has been recognized (La Marche 1974, Scuderi 1987), the important distinction that the effects of temperature and precipitation on growth are nonlinear and multiplicative rather than linear and additive has not been appreciated.”

In a sense what I’m looking for is proof that this fact is now “appreciated” (or, alternatively, has been refuted).

I have been in meetings all day. Came back and there were 7 comments to respond to. Here goes.

#20: Willis. I don’t think anyone really knows the source of these archeological beams that were included. I think that the standard assumption is that they would have been carried from the nearest available site. Since these archeological sites are all at low elevation the closest trees would have been at the lower forest limit. Why bother to carry large beams from higher elevations if there was wood available closer?

#21: My mistake on this one as well. I was also under the mistaken impression that they had used BCP from the lower limits to get precipitation.

#23: I don’t know of any formal studies on the timing of the end of growth. I know that when I have sampled at various times during the growth season that as of mid-July the difference between total growth for the year and that measured with samples taken from a later date (August for instance) showed no apprecible difference. Mid-July still some soil moisture available- late-July to August soil moisture is depleted. I have also not seen much in the way of soil moisture replenishment during summer time rains. The source of the available soil moisture appears to be the winter snowpack.

Also since the trees put on earlywood and latewood in each growth ring you can look at the cell structure in a given years growth to tell if they are still actively adding the larger thinner-walled earlywood cells or if they have transistioned into the thicker, smaller and easily identifiable latewood cells. As per my comment in the preceeding para. mid-July collections are always well into the thicker latewood phase of growth.

Some of the early papers by Fritts may address this issue.

#24: I agree. I would like to see that analysis as well. Perhaps next summer I can go back up to Cirque Peak and resample ten normal growth and ten stripbark growth trees.

#25: Dave. That is pretty close to my thinking on this as well. Large photosynthetic area and root system supplying nutrients/energy for growth to a smaller bark area (partial circumference). Rings get thicker. As for adjustments what are you talking about- standardization like what is done in the early portion of growth? I’ve often thought that the increasing “tail” in the late 1900’s might be in part a function of the standardization approach. In fact Graybill asked me in the late 80’s what standardization approach that I used and whether the difference in his Cirque Peak chronology and mine could be due to different curve fits?

#26: See comment for #23. Steve. yes inversions are common in the valleys causing inverted treelines. I am working on a paper right now that documents this in the southern Sierra and have some additional work ongoing in Australia on the same topic. In essence you can get a temperature sensitive site far below the normal upper treeline.

#27: JAE. I agree. We measure and then correlate temperature and precipitation to growth. T and P may not be the appropriate variables to correlate. The climatologic measures that can strongly influence growth are moisture availability, very low or very high temperatures, and very low solar radiation receipt. They obviously work in interaction with each other. Evapotranspiration would be the end result, however these limiting factors determine whether evapotranspiration is even possible and to what degree.

That’s all for now. Very enjoyable discussion. And seriously- if someone has a specific modeling approach that they want to use on the stripbark versus non-stripbark trees I would be happy to extract cores next summer and collaborate.

I don’t know of any formal studies on the timing of the end of growth. I know that when I have sampled at various times during the growth season that as of mid-July the difference between total growth for the year and that measured with samples taken from a later date (August for instance) showed no apprecible difference. Mid-July still some soil moisture available- late-July to August soil moisture is depleted. I have also not seen much in the way of soil moisture replenishment during summer time rains. The source of the available soil moisture appears to be the winter snowpack.

But if there were moisture in late July-August (thunderstorms, e.g.), growth would continue, right? I have seen studies that show that ring growth continues through August and into Sepetmber if there is adequate moisture. Maybe this would just show up as “noise,” however, since it is not normal?? However, if climate variations caused more late summer rainfall (which seems very possible), then you could have growth spurts that went on for several years. Maybe this is what happened in the case of the infamous bcps that the Team likes? With additional moisture, the CO2 fertilization effect could also happen.

JAE,There might be available moisture but by mid-to-late August air and soil temperatures are already dropping, photoperiod is decreasing and in my observations the trees have already closed down for the year. If you follow the arguements of Korner soil temperatures have by the end of July already dropped to below what is required to support growth. So even if it rained heavily in August and September the effect on growth would be to add to the mositure store for the following year. I haven’t checked but this could be tested. Heavy rain late summer may increase growth the following year.

#24: Perhaps next summer I can go back up to Cirque Peak and resample ten normal growth and ten stripbark growth trees.

That’s a great idea!

#25: Dave. That is pretty close to my thinking on this as well. Large photosynthetic area and root system supplying nutrients/energy for growth to a smaller bark area (partial circumference). Rings get thicker. As for adjustments what are you talking about- standardization like what is done in the early portion of growth?

The trick would be to somehow correct for the proportion of living bark surface area relative to root mass. Not sure if this is feasible in a dendroecological framework. Although spatially, you could sample trees with different bark:root ratios and see if the trend differs.

I’ve often thought that the increasing “tail” in the late 1900’s might be in part a function of the standardization approach. In fact Graybill asked me in the late 80’s what standardization approach that I used and whether the difference in his Cirque Peak chronology and mine could be due to different curve fits?

I don’t know about that; the uptick is pretty severe. It’s probably present in the raw data.

I’m curious, Dr. Scuderi, about your low-frequency, secular-scale growth cycles (Fig. 2 in the Science paper). Could these be spontaneous cycles of decline & recovery, as roots and bark reciprocally try to strike an equilibrium between them?

Dr. Scuderi, you mention some of your work on pinyon pines. I have heard (and seen) that pinyon pines are declining in response to the recent drought. I wonder if bcps are also experiencing increased levels of stress? Any observations there? The reason I ask is I would like to know the probability that bcp went through a period of unusually heavy mortality during the “megadroughts” of the “MWP”.

I asked how they explained the large increase in growth just prior to 1800 AD and also just prior to 1600 AD which I was recording in my Cirque Peak chronology as a sawtooth pattern- and which I knew was in their chronologies as well. I noted that in all likelihood the pre-1600 runup and pre-1800 runup could not be attributed to CO2 fertilization and that in fact they (and the runup that they were attributing to CO2 fertilization) appeared to be part of a periodic ~200 year growth pattern. I never got a good answer from any of the authors about that one.

I am curious about that secular pattern, because it coincides with a pattern that I have recently realized: the so-called “divergence problem” is not just a 20th century phenomenon. With bcps it seems to recur episodically. Like you, I am asking myself: how is this possible? Especially if it is supposed to be CO2 driven?

The pinyons died mainly because of an Ips epidemic (I am not a big fan of the term decline as it is usually used for trees). Of course, you well know that other factors (primarily drought and favorable conditions for extra generations of insects in a season) come into play allowing epidemics of the scale we saw in 2002 and 2003 to occur.

In my area (south-central Utah) we did not see the kinds of extreme mortality that they saw in Arizona, but that could still change as I saw several areas that once again had significant populations this summer after a near total dissapearence of the beetle during the previous summer.

I don’t see a lot of bristlecones around here, but I have not seen any unusual mortality in the ones we do have. The Limber pines (another high-elevation five needle pine) have been getting hit in by mountain pine beetle in what appear to be unusual numbers, but this is very localized – not suprising since populations are widely scattered. There don’t seem to be a lot of good records on species like limber and bristlecones that I come accross (we foresters tend to not wast a lot of resources inventorying noncommercial species even if they are favorites like the limber is for me). I would think that some of the people looking at packrat middens would have some good information. One little summary I read recently mentions the tantalizing detail that limber pines were more common in recent cool periods: http://www.cpluhna.nau.edu/Research/gunnisonchange2.htm , they were even the common pine in the Grand Canyon (instead of pinyon) during the Pleistocene. I would like to have seen that.

Ips notwithstanding, I note that #35 appears to be consistent with the introduction to Dr. Scuderi’s 1987 Nature paper:

“Alpine timberline has been shown to be a definite tension zone between trees and climate where trees invade higher ground during favorable climatic periods and retreat during periods of deteriorating conditions.”

So, it seems possible then, that of the bcps existing during the MWP the “negative responders” (i.e. those predisposed to “geomorphic drought”) were selected out preferentially during the MWP megadroughts.

Nordic,
WRT pinyon pine decline (or whatever you want to call it) how do you separate the effect of drought from the effect of Ips?
According to this report drought is a primary factor and Ips a secondary factor that is partially dependent on drought. If the interaction is this strong then it would be a mistake to attribute this mortality to Ips alone. (I note parallels with southern pine beetle here in the SE.)
If you have read up on the issue, this would be a good place to share a few references. (Though it’s bcps I’m really interested in.)

Bender: No time for a detailed response right now – I have kids to get into bed. I think that we are on the same page. Yes, I agree that drought, and even, “climate change” is the real cause of the die-off of pinyon pine. This may even herald the shift to a new set of vegetative communities with pinyon pine dissapearing from some areas where it is now one of the dominant and characteristic species. Or it may not. You know as well as anyone the difficulties in forecasting future climate. Bark beetles are interesting creatures, it is easy to set off a major outbreak of some of the more aggressive species with only small shifts in stand structure and weather – but we know that rather large shifts have happend repeatedly during the holocene.

Similar “unprecedented” outbreaks seem to be happening with lodgepole and whitebark pines in Montana, Wyoming, and especially Idaho. Some pretty alarming predictions have been made as to the future of those species. Like the pinyon, there are also some old studies pointing to similar outbreaks in the ’30s. Were they as extensive? Its hard to tell, though if you ask Jesse Logan you might get a different answer.

I have read the Breshears paper, but don’t remember enough to be able to comment on it right now. I seem to remember finding some of it informative, other parts less so, some of the speculation annoying and the reporting on it infuriating. Unfortunately (or fortunately, I am never sure) I am not in the research/academic arena so climate science is something I follow because it interests me – and because it may help inform the decisions I make as a forester – this means I don’t keep totally up to date.

As to the decline issue; my graduate training is in plant pathology – specifically forest pathology. In forest pathology decline has a specific meaning, and is a fairly well fleshed-out concept (Mainly the work of Paul Manion). Dr. Manion was a great guy, but the utility of his concept is a matter of debate, particurally because it is often missaplied. I should have taken the time to explain this before. So much for my brief comment;)

Replies:
#34 I agree that somehow quantifing the root mass/bark area would be difficult without adding in a soil/root project- fairly major.

Yes the uptic is in the raw data- however depending on the growth function you use to standardize (neg. exponential, linear, spline, etc.) you get different degrees of uptic in the standardized chronologies.

#35 I am conducting a large scale study over the entire western US (actually from southern Alaska to northern Mexico) looking at we are calling die-off across a range of tree species – we are using satellite imagery, along with field work to attempt to quantify the amount of standing dead (or dying) wood. This is like the Brashears study recently published on pinyon pines but on a much larger scale and for a wide range of species. Interestingly the BCP’s and foxtails that I have observed in California, Nevada, Arizona, Utah, Colorado and New Mexico have not yet shown the same type of die-off that other tree species have shown since 1995 (I would really be interested to know if anyone has seen any evidence of die-off in BCP). Also of interest is our observation that this particular die-off has gone beyond just tree species. Ground surveys have shown significant die-off in sagebrush and creosote- both incredibly drought tolerating species. 100% die-off in sagebrush and creosote in some areas. From everything I have read about earlier die-offs this one is large- but we do not really know how it compares. Dendro records that I have collected from some areas with die-off in pinyon show that many of the trees dying now survived the mid-to-late 1500’s megadrought in the southwest. That particular event did have a severe inpact on pinyon germination in the 1500’s but the spatial pattern of die-off in the 1500’s appears different than the current die-off. Still analyzing this and it is not meant to be a definitive statement.

#36 Yes not just this century!

#37 Pinyons in SE Utah are in very bad shape. Area SE of Glen Canyon has some areas approaching 100% pinyon mortality. Significant mortality has begun in trees in the Henry Mountains. Across the border in Colorado, Mesa Verde has very high mortality (and not just limited to pinyon).

#38 Problem with BCP responding by die-off in the MWP is that they have the ability to survive 300 to 500 years after a downturn in climate. If climate change is persistent and unidirectional for longer than 500 years you see a response at treeline. Otherwise you see lots of really narrow rings on a tree that eventually dies centuries after the downturn begins. If the climate “improves” the tree survives. The tree is still responding to climate like the “happier” members of its cohort 20 to 30 meters lower and the ring growth pattern is the same- just narrower rings. The MWP may not have been long enough to see a major response at treeline.

I’d like to thank you for sharing your knowledge in this forum. This exposure to dendochronology has been eye-opening for me, and I assume for many others as well. I may be reading much into your discussion with bender, but I suspect that he is very intrigued by the science and art of this aspect of paleoclimatology. To be quite honest I wish I could join you in your planned work this upcoming field season.

Thank you, Dr. Scuderi, for a most illuminating discussion. Fascinating to talk to someone who really knows their stuff. If you would like a field assistant for your bcp sampling next summer, I will make myself available for a nine day (1 week + 2 weekends) collecting trip. Thanks again for your participation here.

Some of the images on Google maps are amazing. I’ve identified the location of the Graumlich samples at the following Google. You can match the shapes to an image in Bunn et al 2005 shown below. You can match the shape of the grey valley in the Google map image from 36 37N; 118 22W